This invention is directed to an erosion control device for preventing shoreline erosion in lakes and oceans. It also relates to a method of constructing and installing an erosion control device.
It is well known that a serious problem for riparian owners has been the loss of beaches and other property as a result of wave action in a body of water. Numerous attempts have been made in forming an erosion control structure which will prevent erosion at a reasonable cost. Such an erosion control structure must be able to withstand tremendous forces generated by storms, hurricanes, typhoons and the like.
Certain prior attempts at erosion control are exemplified by U.S. Pat. No. 2,191,924 issued on Feb. 27, 1940 to H. J. Humphrey; U.S. Pat. No. 2,474,786 issued on June 28, 1949 to H. J. Humphrey; U.S. Pat. No. 3,387,458, issued on June 11, 1968 to G. E. Jarian; and U.S. Pat. No. 3,894,397 issued on July 15, 1975 to Samuel S. Fair. Of these the Fair patent is most pertinent because applicants utilized that teaching, found it impractical, and developed this invention to avoid its deficiencies.
Specifically, the structure shown in the '397 patent includes rows and courses of concrete blocks which are longitudinally staggered from each other to provide divided flow passages. Subassemblies of three blocks are bonded together and then formed into a wall by using metal rods or straps to hold them together. This structure and assembly method proved deficient in the following respects. First, because the blocks are not tightly bonded to each other, sand and other entrained material may accumulate between them causing the rods or straps to ultimately give way, thereby destroying the structure. Moreover, wave action can cause the structure to separate longitudinally and cause it to fail. Second, the rods or straps must be put in place in the water, which creates assembly problems and limits the depth of water in which the structure may be built. Third, the straps are corrodable and are subject to failure over a long term simply as a result of rust or friction. Fourth, to provide for divided flow, adjacent rows of blocks may be offset only about 25% which does not maximize the horizontal strength of the structure. Moreover, the divided flow passages cannot be formed in a large cast structure. Fifth, there is no vertical overlap between rows and consequently vertical strength is not maximized. This invention eliminatos the aforementioned difficulties with that prior art structure.